1. Field of the Invention
The invention relates to a reamer having a grinding section with adjustable expansion/contraction and a bore finishing machine comprising the reamer, which are to be employed for finishing of surfaces such as the inner surfaces of cut holes and the inner surfaces of cylinders with high accuracy.
2. Background Art
A reamer having a grindstone section with adjustable expansion/contraction is already known from the specification of U.S. Pat. No. 5,482,498 and from Japanese Utility Model Publication No. Hei 3-29065. According to these documents, the inner peripheral surface of the grindstone section is formed as a tapered surface, a tapered cone or a ball is inserted thereinto, and the tapered cone or the ball is shifted up and down in position with jigs to expand/contract the outer diameter of the grindstone section.
Such adjustment expansion of the diameter with jigs is carried out by hand each time, and the degree of adjustment is slight. A considerable amount of skill is required for the adjustment. It also entails the troublesome process of making several trials of grinding with the diameter-adjusted reamer mounted on the rotation spindle of a grinding machine before final adjustment.
To solve the aforesaid problems of the prior art, it is an object of the present invention to provide a new configuration of a reamer with adjustable expansion/contraction, in which the diameter expansion/contraction of the reamer""s grinding section can be carried out not only using jigs and hands but mechanically despite of adopting a tapered surface as conventional.
Another object of the present invention is to provide a new configuration for a reamer with adjustable expansion/contraction, in which the rotational motion of the main rotation spindle from a motor can be converted into a linear motion from a slide shaft installed in the reamer to mechanically carry out the diameter expansion/contraction of a grinding section of the reamer after the reamer is mounted on a grind finishing machine.
It is yet another object of the present invention to provide a new bore finishing machine comprising a reamer having a grinding section with adjustable expansion/contraction, in which the bore finishing machine can carry out the expansion/contraction adjustment of the reamer""s grinding section as well as grind finishing with the reamer, wherein up-and-down vibration can be applied to a reamer-mounted main rotation spindle by adopting a slanting disk without using an eccentric cum, a spring or a crank.
The foregoing objects and other objects of the present invention have been achieved by the provision of a reamer with adjustable expansion/contraction comprising: a reamer body composed of a hollow shuttle section and a cylindrically shaped grinding section, the shuttle section having a rotation shaft with a built-in threaded cylinder designed so as to be externally operable, the grinding section having a plurality of axially-extending slits provided at equal intervals in its peripheral wall and having a tapered inner peripheral surface extending from the upper section of the slits to an opening end thereof; and a slide shaft provided inside the reamer body, having a threaded shaft at one end and an axial guide hole in the middle section thereof and being connected with a diameter expansion member at the other end thereof. Here, the slide shaft and the rotation shaft are threadedly engaged and connected to each other inside the shuttle section via the threaded shaft, and a guide pin is inserted from the shuttle-section side through the guide hole to convert the rotational motion of the rotation shaft into linear motion of the slide shaft so that the diameter expansion member which is moved with the slide shaft in an axial direction is capable of freely adjusting the outer diameter of the grinding section.
In addition, the grinding section is composed of a diamond grindstone bonded to a base material. The diamond grindstone is of the most appropriate particle size and density selected in accordance with the material and hardness of the particular object to be worked. The diameter expansion member is composed of a tapered cone having an outer peripheral wall formed into the same tapered surface as the tapered inner peripheral surface of the grinding section and a bottom surface with an outer diameter that is approximately the same as the inner diameter of the opening section of the grinding section. Here, the diameter expansion member is integrally connected to the other end of the slide shaft with a bolt that is bolted into the bottom surface thereof so as to be axially moved inside the grinding section with the slide shaft by force.
The foregoing objects and other objects of the present invention have been achieved by the provision of a bore finishing machine comprising a reamer with adjustable expansion/contraction, further comprising: a hollow main rotation spindle for grinding, having a holding section for a reamer body at its lower end and rotatably supported with a housing that can be oriented longitudinally, the housing held with a column so as to be freely liftable upward and downward; a rotation spindle for expansion/contraction of the diameter of the reamer, which is inserted and supported rotatably inside the main rotation spindle, having a pinion on the upper end projecting from the main rotation spindle and having its lower end formed into a joint for connection with a rotation shaft in the reamer body, the connection being provided inside the main rotation spindle; an intermittent gear for intermittent meshing with the pinion to rotate the pinion with the rotation spindle by a set rotational angle; a localization sensor which detects the position of a tooth tip of the intermittent gear and sends out a signal to halt the activation of a drive source for the intermittent gear so that the intermittent gear is always halted out of the meshing point; a main motor for rotation of the main rotation spindle via a transmission mechanism, the main motor being situated on the housing; and a motor for rotation of the rotation spindle via the intermittent gear and the pinion. Here, the rotational motion of the rotation shaft at the lower end of the rotation spindle from the motor is converted into the linear motion of a slide shaft which is screw-threaded with the rotation shaft inside the reamer so that a diameter expansion member on one end of the slide shaft inside the reamer body is capable of adjusting the outer diameter of the grinding section of the reamer.
The transmission mechanism is composed of a rotation cylinder which drives the main rotation spindle and is rotatably supported with the housing while being oriented longitudinally, a transmission shaft situated in the housing so as to be parallel to the rotation cylinder and connected with the drive shaft of the main motor, pulleys integrally arranged on the transmission shaft and on the rotation cylinder at its outer periphery between the rotatably supported sections, respectively, and a belt wound around the pulleys. Also, the rotation cylinder has the main rotation spindle inserted therethrough, and the main rotation spindle is connected with the rotation cylinder via a key member so as to be integral with the rotation cylinder in a rotating direction and movable in an axial direction so that the main rotation spindle can be freely rotated and vertically moved with the rotation spindle for the reamer-diameter expansion accomplished inside thereof.
The bore finishing machine further comprises a vibration applicator for the main rotation spindle composed of: a block-shaped vibrating member for rotatable holding of an upper section of the main rotation spindle passing therethrough; a pair of upper and lower sandwich-supporting rollers provided on one side of the vibrating member and spaced apart by a sandwiching gap; a spinning shaft longitudinally provided inside the housing, which faces the sandwich-supporting rollers and is parallel to the main rotation spindle; a vibrating disk fitted to the spinning shaft with its periphery inserted in the sandwiching gap in a freely tiltable manner and connected with the vibrating member via the pair of sandwich-supporting rollers; a rotating disk fitted and immovably attached to a lower section of the spinning shaft below the vibrating disk, being spaced from the vibrating disk by a required gap; and a joint for connection between the rotating disk and the vibrating disk at their eccentric sections to support the vibrating disk slantingly against the rotating disk with the connecting point as the fulcrum.
The joint is composed of: sleeves fitted to hole sections at the eccentric sections of the vibrating disk and the rotating disk, respectively; spherical bearings installed in the respective sleeves; a connecting shaft consisting of a bolt inserted across the vibrating disk and the rotating disk so as to pass through the bearings; and a nut.
The joint also comprises a circular scale plate fixed to the upper end of the sleeve on the vibrating disk side, and an index member provided on the connecting shaft projecting from a side facing the scale plate, so as to set the vibrating disk at an angle based on the degree of rotation of the connecting shaft indicated by the scale plate and the index member.